Electronic control systems for internal combustion engines

ABSTRACT

An electronic control system for internal combustion engines wherein the duration of injection is proportional to a regulating voltage controlled by at least one operative parameter of the engine. To this end an input voltage defined by a succession of sides of a polygon is subjected to a plurality of transistorized circuits adapted to adjust each the slope of one section of the polygon in accordance with a predetermined parameter.

United States Patent 191 Monpetit et al.

[ 1 ELECTRONIC CONTROL SYSTEMS FOR INTERNAL COMBUSTION ENGINES [76] lnventors: Louis A. Monpetit, l6 Bis Chemin de la Butte, 78 LEtang-Ia-Ville, France; Daniel R. Fournier, l3 Frans Halsstraat, Lisse, Netherlands 221 Filed: Mar. 25, 1974 21 Appl. No.: 454,679

[30] Foreign Application Priority Data Aug. 24 I970 France 70.309l0 [52] US. Cl.. [23/32 EA [5 l] Int. Cl} F02D 5/00 [58] Field of Search 123/32 EA [561 References Cited UNITED STATES PATENTS 3,272,l87 9/l966 Westbrook et al .t l23/32 EA Reichardt l23/32 EA 3,483,85l l2/l969 1 Dec. 30, 1975 3,548,792 l2/l970 Palmer et al. l23/32 EA $566,846 fill 97! Glocker 3,620,l96 ll/l97l Wessel 3,623.46! ll/l97l Rabus 3,646.9l6 3/l972 lnoue et al. l23/32 EA Primary Examiner-Charles J. Myhre Assistant Examiner.loseph A. Cangelosi Attorney, Agent, or Firm-Kenyon & Kenyon Reilly Carr & Chapin [57] ABSTRACT An electronic control system for internal combustion engines wherein the duration of injection is proportional to a regulating voltage controlled by at least one operative parameter of the engine. To this end an input voltage defined by a succession of sides of a polygon is subjected to a plurality of transistorized circuits adapted to adjust each the slope of one section of the polygon in accordance with a predetermined parameter.

20 Claims, 6 Drawing Figures U.S. Patent Dec. 30, 1975 Sheet 1 of 4 Mum l/VVEA/TOKS Laws 4. MONPET/T PAW/E1. R FuQ/v/Eq US. Patent Dec. 30, 1975 shw 2 of4 3,929,108

/NVE/V7URS Lou/5 4. Man/P5777 D4/WEL P Paw/WE? ELECTRONIC CONTROL SYSTEMS FOR INTERNAL COMBUSTION ENGINES This is a continuation, of application Ser. No. 173,543 filed Aug. 20, 197], now abandoned.

The present invention has for its object improvement in electronic injection-controlling means for internal combustion engines. in this technical field the most difficult problem to be solved consists in matching the amount of fuel to be injected with the actual requirements of the engine as defined by one or more readily available regulating parameters.

The main parameter which is the most generally resorted to is constituted in the case of engines provided with a controlled ignition, by the pressure in the admission manifold since such engines are always provided with a throttle valve at the input end of the admission manifold while the pressure depends on the speed of rotation on the degree of opening of the throttle valve and consequently on the load.

Now relationship between the pressure and the amount of fuel to be injected is not a linear function and depends also on the rotary speed of the engine.

it has already been proposed to form this function and to provide a non linear control connection between the pressure collector and the member controlling the duration of injection, which member is constituted in all known control systems by a variable resistance for instance, while furthermore a correction depending on the speed of rotation is executed as provided by a tachometric voltage generator or a variable resistance controlled by a centrifugal regulator which is inserted in the circuit.

in addition to the fact that the corrections thus obtained are merely approximative and the parts resorted to are applicable only to the circuits for which they have been designed, said parts show the serious drawback consisting in that the corrections are performed mechanically; consequently it is necessary to take into account the fact that by reason of the friction arising between the different parts and of their wear, the response curve is not steady and cannot be reproduced at successive times.

The present invention has for its object to cut out these drawbacks and it covers improvements in electronic injection controlling means for internal combus' tion engines, of the type wherein the duration of injection is proportional with a regulating voltage evolved in conformity with at least one operative parameter of the engine. According to the invention an input voltage varying with one operative parameter is transformed into a polygonal curve by means of a circuit including a many transistors as there are sections in the polygon, each of which transistors is connected through its collector with the point connecting two resistances forming a voltage divider, through its base directly or otherwise with the input voltage and through its emitter with the slider of a potentiometric voltage divider through a variable resistance; the position of the slider of said voltage divider defines the operative threshold of the corresponding transistor and, consequently, of the section of the polygon corresponding to said transistor whereas the variable resistance defines the slope of the corresponding polygon section, the regulating voltage being tapped off directly or otherwise at a point between the connecting point between the two resistances forming a voltage divider and the feed voltage.

As a further development of this inventive idea, the invention provides:

a. that each transistor defining a polygon section is associated with an auxiliary transistor through which it is possible to act on the slope of the corresponding polygon section in a direction opposed to the action of the main transistor, the collector of said auxiliary transistor being connected with the base of the corresponding main transistor while its emitter is connected with the slider of a potentiometric voltage divider through a variable resistance and its base is connected with the point connecting the two resistances of a voltage divider of which resistances one is grounded and the other is connected directly or otherwise with the input voltage and also with the base of the corresponding main transistor through a resistance;

b. that the input voltage is applied to the base of a pup or npn transistor inserted through its emitter-collector circuit between ground and a resistance fed by the feed voltage, said pnp or npn transistor serving as an input impedance-matching means adapted to compensate for modifications in temperature in cooperation with the transistor defining the polygon and connected through their bases with the emitter of the impe dance matching transistor, said polygon-defining transistors being of the opposite type npn or pup, the modifications in temperature of the transistors being such that they compensate each other;

e. that that resistance of the two resistances forming a voltage divider, which is inserted between ground and the collectors of the transistors defining the polygon is a variable resistance whereby the whole polygon may be shifted bodily with reference to the axis of ordinates;

d. that the point connecting the resistances forming the voltage divider is connected with the base of a first npn or pup transistor the emitter-collector circuit of which is inserted between the feed voltage and a grounded resistance while a second transistor of the opposite pup or npn type is connected through its base with the emitter of the first mentioned transistor while its emitter-collector circuit is connected with resistances fed by the feed voltage, said connections producing a compensation for the effects of temperature on the regulating voltage tapped off the collector of the second transistor together with a correction multiplying the regulating voltage, a variable resistance being inserted between the feed voltage and the emitter of the second transistor;

e. that two or more circuit systems including a number of transistors defining the sections ofa polygon and two further transistors transforming the voltage thus obtained into a regulating voltage, are connected with a common resistance connected between ground and the connection between the output transistors of the first and of the second systems, each of which systems is fed with an input voltage which is a linear function of one or more operative parameters of the engine, the regulating voltage being then a combination of the polygons obtained through the different systems;

f. that a first circuit system including three transistors defining a three-section polygon is controlled by the pressure in the admission pipe while a second circuit system including three transistors defining another polygon is provided, two transistors forming part of the second system being controlled by the operative temperature of the engine, while the cooperating third transistor is controlled by the rotary speed of the engme;

g. that the regulating voltage is applied to an injection-controlling delay circuit including a program-controllable single-junction transistor. a condenser inserted in parallel with the grounded circuit leading to the anode of said single junction transistor, a transistor the collector-emitter circuit of which is also connected in parallel with said grounded circuit while its base receives the pulse starting the injection, a further transistor being connected through its base with the cathode of the single-junction transistor and having its col lector-emitter circuit inserted between ground and a resistance fed by the feed voltage, the rectangular injection-controlling signal being tapped off the collector of said transistor, the load on said condenser being applied during the locked period of the single-junction transistor under constant current conditions by means of a generator of current compensated with reference to temperature modifications and including a first pnp or n-p-n transistor the emitter collector of which is inserted between a resistance fed by the feed voltage and the anode of the single junction transistor, and a second transistor of the opposite n p n or p n p type connected through its collector with the feed voltage, through its emitter with the base of the first transistor and also with a grounded resistance, the base of said second transistor being set at a predetermined voltage by a voltage divider;

h. that the condenser is the injection controlling delay circuit is loaded by the current generator and also during a short period at the beginning of said loading through the collector-emitter circuit of a transistor and a resistance, the base of said transistor being set at a predetermined voltage by a voltage divider in a manner such that said transistor is conductive when the voltage across the terminals of the condenser is lower than the voltage applied to said base and said transistor is locked when the voltage across the terminals of the condenser reaches and rises above that of the base, taking into account the threshold voltage between the base and the emitter;

i. that the condenser in the injection-controlling delay circuit is loaded by the current generator and also during a short period at the beginning of the loading operation through a diode the anode of which is set at a predetermined voltage by a voltage divider so that said diode is conductive as long as the voltage across the terminals of the condenser is lower than the voltage applied to the anode of said diode and is locked when the voltage across said terminals is higher;

j. that a multiplying correction of the duration of injection, depending on the input voltage is obtained by means of a transistor the collector-emitter circuit of which is inserted between the emitter of the feed transistor operating under constant current conditions in the injection-controlling delay circuit and a variable resistance leading to the slider of a potentiometric voltage divider, the base of said transistor being fed by the input voltage while the variable resistance provides means for adjusting the slope of the multiplying correction and the potentiometric voltage divider provides means for adjusting its operative threshold.

By way of example there is illustrated in the accompanying drawings with a view to furthering the understanding of the invention:

in FlG. l, a simplified diagrammatic view of the injecting system associated with a internal combustion engine,

in P16. 2 a simplified electronic wiring diagram used for controlling the injection;

FIG. 3 a diagram showing the curve of the voltages obtained vs pressure;

FIG. 4 a chart of the different signals produced at different points of the diagram according to FIG. 2;

in H0. 5 a modification of the part P of the circuit according to FIG. 2;

FIG. 6 a diagram showing the curve of the voltages obtained vs pressure in the case of the modification of FIG. 5 is used.

Turning now to FIG. 1, it is apparent that the engine is provided with an input manifold 87 and with electromagnetic injectors 20 fitted in said manifold in the case illustrated. It should be remarked that the injectors may be fitted of course as well in the cylinder head in the case of a direct injection. The electromagnetic injectors 20 are fed with fuel by the pipe system 93 inside which it is subjected to pressure by the pump 92 sucking the fuel out of the container 91 and delivering it through the filter 89. A hydraulic pressure accumulator 88 is provided as also a pressure regulator 90. The injection controlling signals are released by a member I controlled by the rotation of the engine and producing short pulses applied to the injection-controlling delay system Tc which produces in its turn a rectangular signal to be sent to an amplifier A and thence to a distributor D feeding the injector-controlling signals to the injectors 20 in the sequence required for injection. In the ones illustrated, the duration of injection depends on three parameters, to wit the pressure in the admission manifold as measured by the pressure gauge 21, the temperature of the engine cooling water measured by the temperature-measuring means 22 and the rotary speed which is proportional to the frequency of the signals produced by the member controlled by the rotary speed of the engine.

()bviously, these parameters are mentioned only by way of example, since other parameters may be relied on in the arrangement disclosed, such as atmospheric pressure, ambient temperature, the position of the gasthrottling valve and the like. In the case illustrated, the pressure measurement obtained by the gauge 21 is applied to an element Vd which produces a voltage which is a linear function of the pressure. The measurement of the temperature of the water obtained at 22 is applied to an element V, which produces a voltage which is a function of the temperature and lastly the signals produced by the member I are applied to an element V which transforms them into a voltage increasing as a linear function of the rotary speed.

The voltage which is a linear function of the pressure is applied to a circuit section P which transforms said voltage into a voltage the curve defining which is formed by three sides of a polygon, the voltage being thus a continuous function of pressure. The voltage which is a function of the temperature of the cooling water and which is produced by the element V, is applied to a circuit section P which produces a voltage depending on the input voltage fed into it and which is constituted in the present case by a curve comprising two polygon sides of different slopes. Over said voltage, there is superposed a voltage produced by the element E under the action of the voltage produced by the element V controlled by the rotary speed. Said element E,, is designed in a manner such that the modification provided by the rotary speed is effective only starting from a predetermined threshold and changes no more beyond a further threshold of rotary speed. The polygon curves produced by the circuit sections P and P are superposed so as to form an output voltage which is fed to the ignition-controlling delay circuit TC whereby the duration of injection is defined. Said duration of injection may be modified by a multiplying effect as provided by an element EC which applies a signal on said controlling delay circuit TC, said element RC being controlled by the voltage produced by the element V It should be remarked that the action of temperature and speed producing the combined signal passing out of the circuit sections P, and P, forms additive corrections to be incorporated with the main regulating voltage produced by the circuit section P In contradistinction, the correction introduced by the element EC has a multiplying effect and provides an enrichment for fuel when the engine is under full load.

FIG. 2 is a complete electronic wiring diagram of the injection-controlling means. The element V which produces a voltage proportional to the pressure prevailing in the input manifold comprises resistances R R forming a voltage divider and transistors T T,. These transistors are connected so as to form current generators as provided by connecting the base of the transistor T with a point connecting the resistances R, R, while its collector is fed by the feed voltage and its emitter is grounded through the resistance R and is connected with the base of the transistor T, the emitter collector circuit of which is inserted between the feed voltage and the grounded series of resistances R R and R the resistance R being variable and connected with the pressure gauge 21. On the collector of the transistor T there appears a voltage V, which is a linear function of pressure, since the transistors T -T being connected as current generators, any linear shifting of the slider cooperating with the variable resistance R produces a linear modification of the voltage V, by reason of the actual intensity remaining constant. It should also be remarked that the voltage V, is compensated as far as temperature is concerned by the particular connections provided for the transistors T T As a matter of fact, the transistor T may be of the npn type and the transistor T, of the pnp type. Consequently the modifications in the characteristic properties of the transistors produced by modifications in temperature are of opposite directions and therefore compensate each other. The voltage V, which varies according to a linear law as shown in FIG. 3 with reference to the pressure prevailing in the input manifold is applied to the base of the transistor T, forming part of the circuit section P,. The transistor T is of the pnp type and plays the part of an input impedance-matching member ensuring compensation for modifications in temperature for the transistors T T T which are of the npn type. The correction for temperature operates thus in the same manner as in the case of the V,, circuit. The emitter-collector circuit of the transistor T is inserted between the resistance R connected with the supply of voltage and ground. The emitter of the transistor T is furthermore connected with the base of the transistors T T and T The emitters of said transistors are set at a predetermined voltage by connecting said transistors with voltage dividers constituted for T by the resistance R, and the potentiometric voltage divider R for T by the resistance R and the potentiometric voltage divider R and for T by the resistance R and the potentiometric voltage divider R The sliders on said potentiometric voltage dividers R R R are therefore connected with emitters of the corresponding transistors T T T through the variable resistances R,,, R R respectively. The collectors of said transistors T T T are all connected with the point connecting the resistance R with the variable resistance R forming with R a voltage divider, so that said connecting point is subjected to a voltage the value of which varies with the voltage V, applied on the base of the transistor T As a matter of fact, for a position of the slider in the potentiometric voltage dividers R R or R the transistors T T T be come conductive for a predetermined threshold and the slope of the voltage obtained then on the collectors is defined by the resistances R,, R R Therefore the voltage at the point connecting the resistances R and R appears as constituted by three sections each of which depends on the state of conductivity of a transistor. The first section of the polygon corresponds to the case of only one conductive transistor, and the second section corresponds to the case of two conductive transistors the collector currents on which are added. Obviously, the voltage at the point connecting the resistances R R does not increase and in fact decreases with the voltage V, Consequently, it is necessary to provide matching means adapted to provide a voltage which increases with the input voltage V To this end, the output transistors T T which form again here a current generator as provided by applying to the base of the transistor T the voltage appearing at the point connecting the resistances R and R while the collector-emitter circuit of said transistor T, is inserted between the supply of voltage and the grounded resistance R the emitter of the transistor R, being furthermore connected with the base of the transistor T the emitter-cpllector circuit of which connects the variable resistance R connected with the supply of voltage with the grounded resistance R Under such conditions, there is obtained on the collector of the transistor T, a voltage V, which assumes the shape of a polygon as illustrated in FIG. 3.

As in the preceding case, the transistors T-,, T, are compensated as to temperature since they are selected of opposite types pnp and npn. The polygon obtained with the arrangement P can be adjusted in different manners. The release of the transistors T T,, T is defined by the position of the slider on the corresponding voltage dividers R R R The slope of each polygon section is defined by the corresponding variable resistance R R It A further possibility of adjustment is afforded by a parallel vertical shifting of the polygon as provided by the variable resistance R while a multiplying effect is obtainable by the variable resistance R which allows the slopes of the different sections of the polygon to be modified in an uniform manner.

The value of the temperature of the engine cooling water is introduced by means of the element V, which produces a voltage depending on said temperature. To this end, there are inserted in series between the supply of voltage and ground. a resistance R the diode D, and the resistances R and R while the temperature collector constituted in the present case by a thermistance 22 is inserted in parallel with the grounded resis tance R Under such conditions, there is obtained at the point connecting the resistance R, and the diode D, a voltage which is a function of temperature. This latter voltage is applied to the circuit section P,, the connections of which are somewhat similar to those of 7 P,, but provide only two polygon sections. Said polygon sections are produced by the transistors T and T the connections of which are similar to those of the three transistors T T T are provided by the potentiometric voltage divider constituted by the resistance R and the variable resistance R for the transistor T and by the potentiometric voltage divider constituted by the resistance R and the variable resistance R for the transistor II. The sliders in the variable resistances R and R are connected with the emitters of the corresponding transistors T and T through the variable resistances R and R respectively. The collectors of the transistors T and T are connected with the point connecting the collector of the transistor 13 with the resistance R which point is also connected with the base of the transistor T forming part of an output circuit adapted to produce an output voltage in a manner similar to what has been disclosed for the circuit section P To this end, the collector-emitter circuit of the transistor T is inserted between the supply of voltage and the grounded resistance R the emitter of said transistor T being furthermore connected with the base of the transistor T, the emitter-collector circuit of which is also inserted between the resistance R connected with the supply of voltage and the grounded resistance R which is common for both output stages P, and P There is thus obtained on the interconnected collectors of the transistors T, and T, an output voltage to which is constituted by the superposition of a voltage defined by the input voltage V,; which is itself a linear function of the pressure in the input manifold and of a voltage defined by the temperature of the engine-cooling water. The compound voltage obtained is furthermore subjected to a correction as required by the rotary speed of the engine and to this end, the entire polygon illustrated in FIG. 3 is shifted bodily, the polygons Va and Va, appearing in said FIG. 3 corresponding to the voltage depending on the speed of rotation. For this purpose, the element Vv is provided which produces a voltage applied to the base of the transistor T forming part of the element Ev, the value of lastmentioned voltage being a linear function of the rotary speed. Said element Vv includes chiefly the variable resistance R a resistance R a further resistance R a programm-controllable single junction transistor T a resistance R and a resistance R said parts being inserted in series between the supply of voltage and ground. The point connecting the resistance R with the anode of the singlejunction transistor T is connected with one terminal of a grounded condenser C, the point between the resistances R and R is connected with the base of a transistor T Furthermore, the control electrode of the single'junction transistor T is set at a predetermined voltage by the voltage divider constituted by the resistances R and R inserted in series between the supply of voltage and ground. There is also provided a connection between the point connecting the resistances R R and the collecor of the transistor T the emitter of which is grounded. The base of said transistor T is connected on the one hand with the grounded resistance R and on the other hand with the pulse generator I through the resistance R,,. The above mentioned transistor T is grounded through its emitter while its collector is fed by the supply of voltage through the resistance R Furthermore, the collector of T is connected with the base of the transistor T through the resistance R. and with one terminal of the condenser C,, the other terminal of which is grounded. The operation of the element Vv is as follows:

Each time a pulse is produced by the member I, the transistor T becomes conductive and consequently, the condenser C, is discharged and the single-junction transistor T is locked. Immediately, the pulse produced by the member I has disappeared, the transistor T is locked again and the condenser C, begins being reloaded through the resistances R R R when the voltage across the terminals of the condenser C, has reached a predetermined value with reference to the voltage on the electrode controlling the single-junction transistor T the latter becomes suddenly conductive as a consequence of an avalanche effect whereby the transistor T becomes conductive. This ensures a slow discharge of the other condenser C. through the resistance R and the collector-emitter circuit of the transistor T The latter is therefore conductive during the period of conductivity of the programme-controllable single-junction T which period of conductivity depends on the capacity of the condenser C, and on the value of the resistances R R and R and also on the voltage applied on the electrode controlling the singlejunction transistor T The transistor T is therefore alternatingly conductive and locked and the condenser C l is alternatingly loaded in accordance with the condition of the transistor T Therefore, a voltage series across the terminals of the condenser C which voltage depends on the ratio between the durations of the locked condition and of the conductive condition of the transistor T which in its turn depends on the rotary speed of the engine. This voltage is applied on the base of the transistor T the collector of which is connected with the base of the transistor T and the emitter of which is connected with the slider of the potentiometric voltage divider R, through the resistance R Said voltage divider R is inserted in series with the resistance R between the voltage supply and ground. The resistances R R are inserted between the base of the transistor T and the voltage supply while the resistance R,, connects this same base with ground.

The arrangement thus disclosed forms thus the circuit section Ev which allows the output voltage V, to vary with the rotary speed, after the manner of an additive correction.

It should be remarked that the diodes D D,, D, provide compensation for temperature modifications in a manner well-known per se and act in the stead of the auxiliary transistor arrangement referred to elsewhere. The voltage Vs is applied to theinjection-controlling delay system TC through the diode D, and the resistance R The point connecting said diode D, with the resistance R is furthermore connected with the grounded resistances R The delay system TC includes primarily in series between the voltage supply and ground, the resistance R the emitter collector circuit of the transistor T the programme controllable single-junction transistor T the resistance R and the resistance R The condenser C, is inserted between ground and the point connecting the anode of the singleJunction transistor T with the collector of the transistor T There is provided in parallelism with the condenser C, a transistor T the emitter of which is grounded and the collector of which is connected through the resistance R,, with the anode of the single junction transistor T The base of said transistor T is fed with the injection releasing pulses produced by the member l through the diode D and the resistance R Said base of the transistor T is also connected with the grounded resistance R A transistor T is connected fed through its collector with the voltage supply, through its emitter with the base of the transistor T said emitter being grounded through the resistance R while the base of said transistor T 20 is connected with the middle point of the voltage divider constituted by the resistances R R inserted between ground and the voltage supply whereby there is obtained with the transistor T a current generator compensated as to the action of temperature since the two transistors are of opposite types npn and pnp as described for similar pairs of transistors. The injection-controlling signal VTC is tapped off the collector of the transistor T which collector is connected with the voltage supply through the resistance T The base of said transistor T is connected with the point connecting the resistances R and R and its emitter is grounded. The injection-controlling signal VTC feeds the amplifier A beyond which the rectangular signals are transmitted to the injectors 20 in a sequence corresponding to the desired sequence of injection.

The operation of this arrangement is as follows:

Assuming the single-junction transistor T is conductive, the transistor T, is also conductive, and consequently, the collector of said transistor T is substantially at the same voltage as its emitter, that is at ground voltage. Consequently, as long as the transistor T is conductive, the injection cannot be performed since the voltage TVC is then zero. The voltage V across the condenser C, is during this period very low and corresponds with the trough current through the single junction transmitter T When a pulse is applied by the pulse generator I to the base of the transistor T through the diode D and the resistance R the transistor T becomes conductive so that the condenser C, is entirely discharged through the resistance R and the collector-emitter circuit of said transistor T The single junction transistor T is then locked as a consequence of the lack of current, and therefore the transistor T is also locked; the injection controlling signal appears thus on the collector of said transistor T The injection controlling signal appearing on said collector is then applied to the amplifier A. As soon as the pulse is no longer applied on the base of the transistor T,,,, the latter is locked again and the condemmer C is loaded again under constant current conditions through the transistor T Consequently, the voltage V, across the condenser C increases according to a linear law up to a value defined by the voltage applied to the electrode controlling the single junction transistor T which voltage is defined by the output voltage V, of the circuit sections P P,. When thevoltage V, has reached a predetermined value with reference to the voltage V,, the single-junction transistor T is released by an avalanche effect and discharges the condenser C, down to a low value corresponding to the trough current passing through said single-junction transistor T With the restoration of the conductive condition of the single-junction transistor, T the transistor T becomes again conductive and the voltage V drops back to a zero value, which corresponds to the end of the injection. Thus the injection period, registers with the period of non-conductivity of the single junction transistor T which period is defined by a signal of the beginning of injection applied to the base of the transistor T and by the release of said single junction transistor T obtained by an avalanche effect as soon as the load on the condenser C;, has reached a predetermined value while the adjustment of said period is provided by an adjustment of the voltage applied to the electrode controlling said single junction transistor T It should be remarked that the arrangement described still shows a drawback by reason of the operative threshold of the single junction transistor T being equal to about 1.5 volts. Consequently, the ratio between the maximum load of the condenser C and the minimum load of said condenser, as expressed by the voltage V would be too small since the maximum voltage is equal to about 7 volts. To remove this drawback, a high speed loading means CR are provided for the condenser C whereby it is possible to begin with the loading under constant current conditions, at threshold voltage. To this end, the base of a transistor T is set at a predetermined voltage by a voltage divider including the resistances R and R and inserted between the feed voltage and ground. The emitter of said transistor R is connected with the anode of the single-junction transistor T while its collector is connected with the voltage supply through the resistance R By setting the voltage of the base of the transistor T at a suitable value, the condenser C is reloaded very speedily after each discharge following a pulse applied on the base of the transistor T the loading being performed through the resistance R and the collector-emitter circuit of the transistor T When the load voltage T of the condenser C has been reached and thereby the voltage on the emitter of the transistor T has reached a predetermined value with reference to the voltage applied on the base of said transistor, T the latter is locked and the condenser C continues being loaded under constant current conditions through the transistor T The loading curve is then illustrated by the curve b in FIG. 4. lt should be remarked that the transistor T may be replaced by a diode the anode of which is connected with the point connecting the resistances R and R and the cathode of which is connected with the anode of the single-junction transistor T The operation is the same as that disclosed hereinabove: the diode remains conductive as long as the voltage applied to its anode lies above the voltage V,.. When said voltage V,. has reached the value of said anode voltage, the diode is no longer conductive and the loading continues as precedingly through the transistor T The circuit section EC described hereinafter is intended to increase the richness of injection, that is, it ensures an increase in the duration of injection with a multiplying effect depending on the action arising in the input manifold. This enrichment is intended for an engine operating under maximum power conditions. For this purpose the base of the transistor T is fed with a voltage V, which is proportional to the pressure in the admission manifold, the collector of said transistor T being connected with the emitter of the transistor T and its emitter being connected with the slider of a potentiometric divider R through the variable resistance R The voltage divider R is inserted in series with the resistance R,, between the supply of voltage and ground, so as to shunt a fraction of the current passing through the resistance R and to reduce proportionally the current loading the condenser C whereby the duration of loading and that of the injection is increased. The potentiometer R provides means for adjusting the starting of the operation of the transistor T in a manner such that this fraction of 1 1 current is shunted only beyond a predetermined threshold, the value of the shunted current which is defined by the voltage Ve being adjusted by the variable resistance R,,.

Birefly stated, the circuit section Vd produces a voltage Ve which .is a linear function of the pressure in the input manifold of the engine, which voltage is transformed by the circuit section P and P,, into a polygonshaped voltage Vs the shape of which depends furthermore on the temperature of the engine-cooling water. Moreover the bodily shifting of the polygon is controlled by the rotary speed of the engine through the circuit sections V, and EV, which leads to the obtention of polygon Va,, Va, Va,, according to the rotary speed as shown in FIG. 3. Thespolygon-shaped voltage V, is applied to the injection-controlling circuit section TC and defines the duration of injection as disclosed hereinabove. FIG. 4 shows how said circuit section TC receives the injection-releasing pulse from the pulse generator I (see curve a of GIG. 4). This pulse causes a rectangular pulse V to appear at the output of the circuit section TC beyond which it enters the amplifier A. During this time, the voltage across the terminals of the condenser C, increases as shown by the curve b of FIG. 4 and defines the duration of injection.

Obviously, the invention is not limited to the invention described and varioius circuit sections P,, P, may be designed so as to take into account various operative parameters of the engine and to form voltage polygons the number of sections of which depends on the number of transistors in the circuit section P,. Furthermore the voltage V, may be applied on the bases of the transistors T,, T,, T, either directly or else through an auxiliary transistor as illustrated in FIG. 2. It should also be well understood that the feed voltage is a stabilized voltage. Lastly, the shape of the curves showing the input voltage Ve and of the output voltage V, may be different from that illustrated in FIG. 3, in which case the input voltage V, is a linear function of the pressure P while the output voltage V, shows a polygonal outline the straight sides of which extend with slopes increasing with the pressure P.

Now, in certain cases, the input voltage V, may be a non-linear function of the pressure P, so that the output voltage V, has a polygonal outline the sections of which are curvilinear. Similarly, the slopes of the polygon sections may obviously decrease with increasing pressures, without this widening the scope of the invention as defined by the accompaning claims.

FIGS. 5 and 6 illustrate an embodiment providing such a non-linear curve for the input voltage V,.

Said input voltage V, which forms a non-linear function of the pressure P in the input manifold is applied to a transforming circuit P', as provided by feeding with said voltage the base of the transistor T,, the emitter of which is connected with the voltage supply through the resistance R, and the collector of which grounded. The emitter of said transistor is furthermore connected with the bases of the transistors T,, T, through the corre sponding resistances R and R the emitters of said transistors T, and T, being set at a predetermined voltage by means of a voltage divider constituted by the resistance R, and the potentiometer R for the transistor R, and the resistance R and the potentiometer R,, for the transistor T The sliders of said potentiometers R -R are connected respectively with said emitters of the transistors T,, T, through the corresponding vari able resistances R,-R,,. These connections are similar to those described with reference to FIG. 2 except for the fact that between the main transistors T,, T, there are provided further transistors T,-T', the emitters of which are also set at a predetermined voltage by means of a voltage divider including the resistance R',, the potentiometer R and the variable resistance R, for the transistor R, and the resistance R',,, the potentiometer R',, and the variable resistance R for the transistor T',. The collectors of said transistors T,-T', are connected with the bases of the corresponding main transistors T,, T, while their bases are connected with the points connecting the resistances R -R- and R -R respectively, said resistances R -R being inserted in series between the emitter of the transistor T, and ground. The collectors of the transistors T,-T, are connected as in the case of FIG. 2 with the point connecting the resistance R with the variable resistance R,,, which point is connected furthermore with the base of the transistor T the collector of which is fed by the supply of voltage while its emitter is grounded through the resistance R and is connected with the base of the transistor T,. The emitter of the latter is connected with the feed supply through the variable resistance R and its collector is grounded through the resistance R,,. The output voltage V, appears then on the collector of the transistor T, and assumes for instance the shape illustrated in FIG. 6. In fact, the transistors T',, T,, T, and T, produces a current depending on the voltage applied on their bases and on the position selected for the potentiometer sliders R' R R',,, R and on the adjustment of the variable resistances R',, R,, R' R A suitable adjustment of these different parts ensures the locking of the transistors T, T,, T, while the transistor T, remains conductive up to a predetermined value of the input voltage V, so that the output voltage V, is given out then by the section a of the polygon. Above said predetermined value of the input voltage V,, the transistor T, becomes conductive so that the base of the transistor T, is subjected to a constant voltage and consequently the output voltage is also constant. This corresponds to a horizontal section b of the polygon. When the input voltage V, reaches a higher value, the transistor T, becomes conductive and consequently the output voltage is given out by the polygon section a until the transistor T, becomes conductive and acts on the transistor T This provides a further constant value of the output voltage V, as shown by the horizontal section b. Obviously the shape of the curve is given solely by way of exempliiication and according to the adjustment performed on the potentiometers. R',,; R R',,, R], and on the variable resistances R,, R,, R' R the starting of the opera tion of the transistors and the slopes of the curves may be varied as desired with a view to obtaining any type of curves, for instance a polygonal outline the sections a, b, a'b' of which assume slopes which decrease from one section to the next without however reaching horizontality, the example illustrated corresponding thus to a borderline case.

What we claim is:

1. in an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronic control system being of the type that includes means for generating a regulating 13 voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises:

means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncyclical input voltage having a magnitude that is at all times a function of the one engine operating parameter and means responsive to the magnitude of the input voltage for generating an output voltage having a magnitude that at all times is a predetermined nonlinear function of the input voltage, the curve of the output voltage as a function of the input voltage consisting of a predetermined plurality of curve segments having different average slopes.

2. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises:

means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncylical input voltage having a magnitude that is at all times a function of the one engine operating parameter and a plurality of transistor circuits having their inputs connected to the input voltage and their outputs connected to a common load resistance, each transistor circuit being biased to a different predetermined conduction threshold voltage, for generating an output voltage having a magnitude that at all times is a predetermined nonlinear function of the input voltage, the curve of the output voltage as a function of the input voltage consisting of a plurality of curve segments having different average slopes, the number of segments being equal to the number of transistor amplifiers.

3. The injection control system of claim 2 further comprising:

at least one auxiliary transistor connected in the input circuit of one of the transistor circuits, the auxiliary transistor being biased to a predetermined conduction threshold voltage for opposing the effect of the input voltage upon the output of the associated transistor circuit when the input voltage is above the predetermined threshold voltage of the auxiliary transistor.

4. The injection control system of claim 3 comprising a separate auxiliary transistor associated with each of the plurality of transistor circuits.

5. In an electronic system for controlling the duration of injections in a fuel injection internal combustion 14 engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises:

means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncylical input voltage having a magnitude that is a function of the one engine operating parameter; source of substantially constant voltage; plurality of main transistors having their collectors connected together through a common load resistance to one terminal of the voltage source and each transistor having its emitter connected through a separate biasing circuit to the other terminal of the voltage source, each biasing circuit being set for a different predetermined conduction threshold voltage on the base of its associated transducer, the input voltage being applied to the bases of the main transistors for generating an output voltage across the load resistance is as a nonlinear function of the one operating parameter, the curve of the output voltage as a function of that parameter consisting of a plurality of curve segments having different predetermined average slopes, the number of segments being equal to the number of main transistors. 6. The injection control system of claim 5 wherein each biasing circuit comprises:

a potentiometer connected as a voltage divider across the terminals of the voltage source and a variable resistance having one terminal connected to the movable contact of the potentiometer and the other terminal connected to the emitter of its associated main transistor, where-by adjustment of the movable contact of the potentiometer establishes the predetermined conduction threshold of the associated transistor, and adjustment of the variable resistance establishes the predetermined average slope of the output curve segment corresponding to the associated transistor. 7. The injection control system of claim 5 further comprising:

at least one auxiliary transistor having its collector connected to the base of one of the main transistors and its emitter connected through a biasing circuit to the other terminal of the voltage source, the biasing circuit being set for a predetermined conduction threshold voltage on the base of the auxiliary transistor, and the input voltage being applied through a first resistance to the base of the auxiliary transistor and through a second resistance to the junction between the base of the main transistor and the collector of the auxiliary transistor, whereby the auxiliary transistor opposes the effect of the input voltage on the collector current of the main transistor when the base voltage of the auxiliary transistor is above the predetermined conduction threshold voltage.

8. The injection control system of claim 5 wherein all of the main transistors are of the same polarity type, the system further comprising:

an emitter-follower circuit having a transistor of op posite polarity type interposed between the input voltage and the bases of the main transistors for serving as an impedance-matching unit and for compensating the effect of temperature variations on the operation of the main transistors.

9. The injection control system of claim 5 further comprising:

a variable resistance connected between the junction of the common load resistance and the collectors of the main transistors and the other terminal of the voltage source, whereby adjustment of the variable resistance produces vertical shifting of the output voltage curve.

10. The injection control system of claim 5 further comprising:

an emitter-follower, including a transistor of one polarity type having its base connected to the junction between the collectors of the main transistors and the common load resistance and an output amplifier stage, including a transistor of polarity type opposite to that of the emitter-follower transistor having its base connected to the emitter of the emitterfollower and its emitter and collector connected through first and second resistors, respectively, across the voltage source, the regulating voltage appearing as an inversion of the output voltage curve on the collector of the output transistor, whereby the opposite polarity types of the emitter-follower and output amplifier transistors provide temperature compensation for the regulating voltage.

11. The injection control system of claim 5 wherein the first resistor is a variable resistor for providing a multiplying adjustment to the values of the regulating voltage.

12. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and at least one means for sensing a corresponding number of operating parameters, of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of at least one such engine operating parameter and means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises:

means, adapted for connection to a means for sensing a first operating parameter of such an engine for generating a first noncylical input voltage having a magnitude that at all times is a function of the first engine operating parameter;

means responsive to the magnitude of the first input voltage for generating a first output voltage having a magnitude that at all times is a predetermined nonlinear function of the first input voltage, the curve of the first output voltage as a function of the first input voltage consisting of a first predeter- 16 mined plurality of curve segments having different average slopes;

means, adapted for connection to a means for sensing a second operating parameter of such an engine for generating a second noncylical input voltage having a magnitude that at all times is a function of the second engine operating parameter;

means responsive to the magnitude of the second input voltage for generating a second output voltage having a magnitude that at all times is a predetermined nonlinear function of the second input voltage, the curve of the second output voltage as a function of the second input voltage consisting of a second predetermined plurality of curve segments having different average slopes; and

means for combining the first and second output voltages to form the regulating voltage.

13. The injection control system of claim !2 further comprising:

means, adapted for connection to a means for sensing a third operating parameter of such an engine for generating a third noncylical input voltage having a magnitude that at all times is a function of the third engine operating parameter; and

means responsive to the magnitude of the third input voltage for modifying the magnitude of the second output voltage as a function of the third operating parameter.

14. The injection control system of claim 13 wherein the first engine operating parmeter is intake manifold pressure, the second operating parameter is the operative engine temperature, and the third operating parameter is engine speed.

15. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine of the type that includes a pulse generator synchronized with engine rotation for generating short triggering pulses corresponding to each injection period, means for generating a regulating voltage having an amplitude that is a function of at least one engine operating parameter, and means for generating successive fuel injection signals, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating fuel injection signals comprises:

a source of substantially constant voltage;

a programmable unijunction transistor having its cathode connected through a load resistor to the negative terminal of the voltage source and its control electrode connected to the output of the regulating voltage generator;

a constant current generator connected between the anode of the programmable unijunction transistor and the positive terminal of the voltage source; capacitor connected between the junction of the constant current generator and anode of the programmable unijunction transistor and the negative terminal of the voltage source; first transistor having its base connected to a point between the cathode of the programmable unijunction transistor and the load resistor and its collector-emitter circuit connected in series with a second resistor across the voltage source; and a second transistor having its collector-emitter circuit connected to the junction between the capacitor and the anode of the programmable unijunction transistor and the negative terminal of the voltage source and its base connected to the output of the comprising:

a second current generator connected between the positive terminal of the voltage supply and the capacitor for charging the capacitor at an increased rate as long as the voltage across the capacitor is less than a predetermined value.

17. The injection control system of claim 16 wherein the second current generator comprises:

a voltage dividing network connected across the volt age source and a third transitor having its collector-emitter circuit connected between the positive terminal of the voltage source and the capacitor and its base connected to a point on the voltage divider having a predetermined voltage such that the third transistor will conduct only when the capacitor voltage is less than the difference between the predetermined voltage and the base-emitter threshold voltage of the third transistor.

18. The injection control system of claim 16 wherein the second current generator comprises:

a voltage dividing network connected across the voltage source and a diode having its cathode connected to the capacitor and its anode connected to a point on the voltage divider having a predetemined voltage, whereby the diode will conduct only when the capacitor voltage is less than the predetermined voltage.

19. The injection control system of claim 15 further comprising:

means for correcting the duration of the injection signals as a direct function of the intake manifold pressure.

20. The injection control system of claim 19 wherein the means for correcting the duration of each injection signal as a function of intake manifold pressure comprises:

means for generating an input voltage that is proportional to the intake manifold pressure;

a fourth transistor having its base connected to the input voltage generator and its collector-emitter circuit connected in series with a biasing circuit between the output of the constant current generator and the negative terminal of the voltage source for shunting a portion of the capacitor charging current from the constant current generator whenever the input voltage is greater than the conduction threshold of the fourth transistor as determined by the biasing circuit.

PATENT NO.

DATED |NVENTOR(S) Louis A. Monpetit and Daniel R. Fournier It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01. Col.

[sen] UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION line line line line line line line line line line line line line line line line line line line line ,929,l08 ecember 30, 1975 54, change "a" to -as;

20, change "pnp" to --pup;

2, change "program" to -programme; 30, change "ones" to --case-;

9, change "RC" to -EC--;

17, change "for" to --of;

3, change "are" to as--;

29, change "to" to Vs-;

45, change "program" to --programme-;

27, change "series" to -arises-;

39, change "R to -R 55, change "resistances to -resistance; 31, change "TVC" to -VTC-;

47, change "condemmer" to -condenser;

55, change "V 20, change "GYG" to FIG--; 21, change "V to V 7, change "R'" to a 28, change "emitterfollower" to --emitter-follower 37, change "claim 5" to --claim l0-.

c. mnsmu. mum

U11! .IASON R c ('flmml'uioner uj' Puma: and Trademarks A Nesting Offim 

1. In an electronic system for controLling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises: means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncyclical input voltage having a magnitude that is at all times a function of the one engine operating parameter and means responsive to the magnitude of the input voltage for generating an output voltage having a magnitude that at all times is a predetermined nonlinear function of the input voltage, the curve of the output voltage as a function of the input voltage consisting of a predetermined plurality of curve segments having different average slopes.
 2. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises: means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncylical input voltage having a magnitude that is at all times a function of the one engine operating parameter and a plurality of transistor circuits having their inputs connected to the input voltage and their outputs connected to a common load resistance, each transistor circuit being biased to a different predetermined conduction threshold voltage, for generating an output voltage having a magnitude that at all times is a predetermined nonlinear function of the input voltage, the curve of the output voltage as a function of the input voltage consisting of a plurality of curve segments having different average slopes, the number of segments being equal to the number of transistor amplifiers.
 3. The injection control system of claim 2 further comprising: at least one auxiliary transistor connected in the input circuit of one of the transistor circuits, the auxiliary transistor being biased to a predetermined conduction threshold voltage for opposing the effect of the input voltage upon the output of the associated transistor circuit when the input voltage is above the predetermined threshold voltage of the auxiliary transistor.
 4. The injection control system of claim 3 comprising a separate auxiliary transistor associated with each of the plurality of transistor circuits.
 5. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and means for sensing one operating parameter of an engine, said electronIc control system being of the type that includes means for generating a regulating voltage that is a function of such an engine operating parameter and timing means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises: means, adapted for connection to a means for sensing one operating parameter of such an engine, for generating a noncylical input voltage having a magnitude that is a function of the one engine operating parameter; a source of substantially constant voltage; a plurality of main transistors having their collectors connected together through a common load resistance to one terminal of the voltage source and each transistor having its emitter connected through a separate biasing circuit to the other terminal of the voltage source, each biasing circuit being set for a different predetermined conduction threshold voltage on the base of its associated transducer, the input voltage being applied to the bases of the main transistors for generating an output voltage across the load resistance is as a non-linear function of the one operating parameter, the curve of the output voltage as a function of that parameter consisting of a plurality of curve segments having different predetermined average slopes, the number of segments being equal to the number of main transistors.
 6. The injection control system of claim 5 wherein each biasing circuit comprises: a potentiometer connected as a voltage divider across the terminals of the voltage source and a variable resistance having one terminal connected to the movable contact of the potentiometer and the other terminal connected to the emitter of its associated main transistor, whereby adjustment of the movable contact of the potentiometer establishes the predetermined conduction threshold of the associated transistor, and adjustment of the variable resistance establishes the predetermined average slope of the output curve segment corresponding to the associated transistor.
 7. The injection control system of claim 5 further comprising: at least one auxiliary transistor having its collector connected to the base of one of the main transistors and its emitter connected through a biasing circuit to the other terminal of the voltage source, the biasing circuit being set for a predetermined conduction threshold voltage on the base of the auxiliary transistor, and the input voltage being applied through a first resistance to the base of the auxiliary transistor and through a second resistance to the junction between the base of the main transistor and the collector of the auxiliary transistor, whereby the auxiliary transistor opposes the effect of the input voltage on the collector current of the main transistor when the base voltage of the auxiliary transistor is above the predetermined conduction threshold voltage.
 8. The injection control system of claim 5 wherein all of the main transistors are of the same polarity type, the system further comprising: an emitter-follower circuit having a transistor of opposite polarity type interposed between the input voltage and the bases of the main transistors for serving as an impedance-matching unit and for compensating the effect of temperature variations on the operation of the main transistors.
 9. The injection control system of claim 5 further comprising: a variable resistance connected between the junction of the common load resistance and the collectors of the main transistors and the other terminal of the voltage source, whereby adjustment of the variable resistance produces vertical shifting of the output voltage curve.
 10. The injection control system of claim 5 further comprising: an emitter-follower, including a transistor of one polariTy type having its base connected to the junction between the collectors of the main transistors and the common load resistance and an output amplifier stage, including a transistor of polarity type opposite to that of the emitter-follower transistor having its base connected to the emitter of the emitterfollower and its emitter and collector connected through first and second resistors, respectively, across the voltage source, the regulating voltage appearing as an inversion of the output voltage curve on the collector of the output transistor, whereby the opposite polarity types of the emitter-follower and output amplifier transistors provide temperature compensation for the regulating voltage.
 11. The injection control system of claim 5 wherein the first resistor is a variable resistor for providing a multiplying adjustment to the values of the regulating voltage.
 12. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine having electrically actuated means for cyclically injecting fuel during discrete time periods in response to successive fuel injection signals of predetermined duration and at least one means for sensing a corresponding number of operating parameters, of an engine, said electronic control system being of the type that includes means for generating a regulating voltage that is a function of at least one such engine operating parameter and means responsive to the regulating voltage and to the operating cycle of such an engine for generating successive fuel injection signals in successive engine cycles, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating the regulating voltage comprises: means, adapted for connection to a means for sensing a first operating parameter of such an engine for generating a first noncylical input voltage having a magnitude that at all times is a function of the first engine operating parameter; means responsive to the magnitude of the first input voltage for generating a first output voltage having a magnitude that at all times is a predetermined nonlinear function of the first input voltage, the curve of the first output voltage as a function of the first input voltage consisting of a first predetermined plurality of curve segments having different average slopes; means, adapted for connection to a means for sensing a second operating parameter of such an engine for generating a second noncylical input voltage having a magnitude that at all times is a function of the second engine operating parameter; means responsive to the magnitude of the second input voltage for generating a second output voltage having a magnitude that at all times is a predetermined nonlinear function of the second input voltage, the curve of the second output voltage as a function of the second input voltage consisting of a second predetermined plurality of curve segments having different average slopes; and means for combining the first and second output voltages to form the regulating voltage.
 13. The injection control system of claim 12 further comprising: means, adapted for connection to a means for sensing a third operating parameter of such an engine for generating a third noncylical input voltage having a magnitude that at all times is a function of the third engine operating parameter; and means responsive to the magnitude of the third input voltage for modifying the magnitude of the second output voltage as a function of the third operating parameter.
 14. The injection control system of claim 13 wherein the first engine operating parmeter is intake manifold pressure, the second operating parameter is the operative engine temperature, and the third operating parameter is engine speed.
 15. In an electronic system for controlling the duration of injections in a fuel injection internal combustion engine of the type that includes a pulse generatoR synchronized with engine rotation for generating short triggering pulses corresponding to each injection period, means for generating a regulating voltage having an amplitude that is a function of at least one engine operating parameter, and means for generating successive fuel injection signals, each signal having a duration depending on the amplitude of the regulating voltage, the improvement wherein the means for generating fuel injection signals comprises: a source of substantially constant voltage; a programmable unijunction transistor having its cathode connected through a load resistor to the negative terminal of the voltage source and its control electrode connected to the output of the regulating voltage generator; a constant current generator connected between the anode of the programmable unijunction transistor and the positive terminal of the voltage source; a capacitor connected between the junction of the constant current generator and anode of the programmable unijunction transistor and the negative terminal of the voltage source; a first transistor having its base connected to a point between the cathode of the programmable unijunction transistor and the load resistor and its collector-emitter circuit connected in series with a second resistor across the voltage source; and a second transistor having its collector-emitter circuit connected to the junction between the capacitor and the anode of the programmable unijunction transistor and the negative terminal of the voltage source and its base connected to the output of the pulse generator for discharging the capacitor and blocking the programmable unijunction transistor in response to each triggering pulse from the pulse generator to initiate a corresponding rectangular injection signal at the collector of the first transistor, the capacitor being recharged at a predetermined rate upon termination of the triggering pulse until the capacitor voltage reaches a value, in relation to the regulating voltage on the control cathode of the programmable unijunction transistor, that triggers the unijunction transistor and terminates the rectangular injection signal.
 16. The injection control system of claim 15 further comprising: a second current generator connected between the positive terminal of the voltage supply and the capacitor for charging the capacitor at an increased rate as long as the voltage across the capacitor is less than a predetermined value.
 17. The injection control system of claim 16 wherein the second current generator comprises: a voltage dividing network connected across the voltage source and a third transitor having its collector-emitter circuit connected between the positive terminal of the voltage source and the capacitor and its base connected to a point on the voltage divider having a predetermined voltage such that the third transistor will conduct only when the capacitor voltage is less than the difference between the predetermined voltage and the base-emitter threshold voltage of the third transistor.
 18. The injection control system of claim 16 wherein the second current generator comprises: a voltage dividing network connected across the voltage source and a diode having its cathode connected to the capacitor and its anode connected to a point on the voltage divider having a predetemined voltage, whereby the diode will conduct only when the capacitor voltage is less than the predetermined voltage.
 19. The injection control system of claim 15 further comprising: means for correcting the duration of the injection signals as a direct function of the intake manifold pressure.
 20. The injection control system of claim 19 wherein the means for correcting the duration of each injection signal as a function of intake manifold pressure comprises: means for generating an input voltage that is proportional to the intake manifold pressure; a fourth transistor having its base connected to the input voltagE generator and its collector-emitter circuit connected in series with a biasing circuit between the output of the constant current generator and the negative terminal of the voltage source for shunting a portion of the capacitor charging current from the constant current generator whenever the input voltage is greater than the conduction threshold of the fourth transistor as determined by the biasing circuit. 